Brake mechanism for automotive vehicles



Api-il 18, 1933. yc. s. .BRAGG Er AL. 1,904,266

BRAKE MECHANISM FOR AUToMTIvEI-vmclgs Filed Dec. 12, 1927 I 3 Sheets-Sheet l April 18.. 1.933. Y Q s, BRAGG Er AL I 1,904,266

BRAKE MECHANISM FOR ATOMOTIVE VEHICLES Filed Dec. 12, 1927 `sheets-sheet 2 April 18, 1933-:

c. s. BRAGG Er 'AL BRAKE MECHANISM FOR AUTOMOTIVE VEHICLES Filed Dec. 12, i927 3 Sheets-Sheet 5 Patentedl Apr. 1.3, 1935 STATES tanzte PATENT OFFICE CALEB S. BRAGG, 0F PALM REACH, FLORIDA, l.AND VECTOR W. IKLIESRATH, 0F PORT WASHIN'GTON, NEW YORK, ASSIGNORS TO BRAGGfKLIESRATH CORPORATION, 0F LONG ISLAND CITY, NEW YORK, A CORPORATION OF. NEW YORK BRAKE 'MECHANISM FOR AUTOMOTIVE VEHICLES lAppication lred December 12, 1927. Serial No. 239,444.

Our invention consistsin the novel features hereinafter described, referencevbeing had to the accompanying drawings which show two embodiments of the invention selected by us for purposes of illustration, and the said invention is fully disclosed in the following description and claims. p

The object of our invention is to provide a pair of brake mechanisms for a pair of wheels of an automotive vehicle located opposite toy each other transversely of the vehicle with a, power actuator comprising a cylinder andpiston for operating them by power obtained by the differential of higher and lower fluid pressures, most conveniently atmospheric pressure operating against a partial vacuum or rarification obtained for example from the throttle controlled suction passage of an internal combustion engine which drives the vehicle (or other source of suction), the cylinder andthe piston being both movable with respect to each other and with respect to the chassis of the vehicle, the piston being connectedl to one-brake mechanism and the cylinder to the other so that the power of the actuator-will always be applied equally to the brake mechanisms for both wheels without regard to the individual adjustments of the brake mechanisms or wear of brake linings, the stroke of the piston in the cylinder being suiiciently long to compensate forA considerable wear of the brake linings and obviating frequent adjustments in f the connections thereto, an operator operated part, which preferably vcontrols the valve mechanism for the actuator, being connected with both brake mechanisms, so that the operator may apply his physical force equally thereto in addition to that of the power actuator, or to operate them independently of the actuator, in which case the valve mech- Aanism is preferably first moved into position to vent the actuator cylinder and prevent compression therein, and a single adjusting means may be provided in the connection beu tween the valve mechanism and the brake mechanism to prevent the operator operated vpart (usually the pedal'lever) from striking a part or device' which limits its movement as`the brake ligs wear, should the throw of the operator operatedfpart bel less than the stroke f the piston and cylinder. Our

invention permits of the use of a smaller and i cheaper power actuator for any given power required, and less air is therefore withdrawn into the suction source, with less danger of interfering with the operation of the engine or stalling it if idling where the suction is obtained from the suction passage ofthe engine;` equalization in the application of force both of the actuator and of the operator is secured and only one adjustment need Fig. 3 is a detail sectional view of onei vform of controlling valve mechanism which may be employed for the actuator.

Figa 4, 5 and 6 are views similar respectively to Figs. 1, 2 and 3, but illustrating a slight modification.

, Fig. 7 is a diagrammatic plan view similar tb Fig. l, illustrating another modification of our invention. f Fig. 8 is a detail view showing anothel slight modification.

i lFigs. 1, 2 and 3 illustrate a very simple. einbodiment of our invention in which C repre sents the chassis of an automotive vehicleof which W, W1, are a pair of oppositely disposed wheels, as the rear or driving'wheels, driven in any usual or preferred manner by aninternal combustion engine, 60, provided with the usual suction passage, 61, of which the intakevmanifold, 62, is a part, carburetor, 64, and throttle valve, 63, between the carburetor and the engine cylinders. B, B1, represent the independent brake mechanisms for wheels, W, W1, which may he of any desired typeand areshown in this instance for 'example as com rising each a brake drum, 70,

brake band, 1., and 'brake lever, 72, fwith its retracting spring, 73.

lli, L, represent a pair of three armed levers, the arms of which are set at any desired angles to each other and united at the pivotal point, 83, thereof, said levers being pivoted to brackets, 90, secured to the chassis adjacent to opposite sides of the vehicle, each 1ever having in this instance an arm, 80, connected by a link, 74, with the adjacent brake lever, 72, a second arm, 81, extending transversely of the 'chassis on the other side of the point of pivoting, 83, of the-lever, and a third arm, 82, substantially perpendicular to the arms, 80 and 81. Between the arms, 82, of

the respective levers, L, L, we interpose a power actuator comprising a cylinder, 1, and a piston, 3, each of which is connected to one of said arms, 82. In this instance the cylinder, 1', is shown pivotallyconnected to and supported by one arm, 82, the piston being provided with a piston rod, 5, pivotally connected to the other arm, 82. The arms, 81, extend toward each other and are pivotally connected to opposite ends of a connecting link, 84, the pivot pins, 85, engaging slotted apertures, 85a. It will be understood that both the cylinder and the piston are movable with the respective arms, 82, to which they are connected.

The actuator is provided with suitable controlling valve mechanism, and in this instance We have shown a form of valve mechanism covered by our former Letters Patent of the United States No. 1,731,041 patented October 8th, 1929. Briey this valve mechanism comprises a valve casing, 10, provided with a central valve chamber, 16, in which are located two opposit'ely disposed valves, 40 and 41, the casing being provided with apertures, 11 and 12, on opposite sides of the chamber, and the chamber being connected with the closed end of the 'cylinder through a hollow valve actuating sleeve, 20, movable with 'and with respect to the valve casing and valves, and having an aperture, 27, communicating with the chamber, 16, between the valves, and a tting, 29, outside of the casin havin an ear, 30, and a connection, 31, to w ich a exible tubular connection with the cylinder can` be connected. The valves are normally pressed toward their seats atopposite ends of Ichamber, 16, by yielding means, 50, and sealingly engage the sleeve, 20, which is provided with collars, 40a and 41, so located as to eiect the opening of one valve after permittin the other to close, by a movement of the va ve sleeve in either direction with r ect to the valve casing and permitting 'ht 88, pivoted at 88, to the chassis, and provided with a retracting spring, 89, said lever being connected below its pivot vby a link, 75, to the valve casing, 16, the valve actuating sleeve, 20, being connected by a link, 76, to the center of the link, 84, a turn buckle, 77, of well known construction, provided with a threaded adjusting wing nut, 78, (or other adjustable means) being interposed between the link, 76, and the link, 84, to Vary the effective length of the link, 76. We also provide an adjustable stop, 91, consisting in this instance of a set screw in a bracket, 92, secured to the chassis, vfor engaging a collar, 93, on the valve actuating sleeve, 20, to determine the position of the brakes and valve mechanism in the released position.

In the installation illustrated in Figs. 1 and 2, the aperture, 12, of the valve casing is connected with a source of suction, being connected in this instance by a suction pipe, 65, a portion, 65a, of which is flexible, with the suction passage of the engine between the throttle valve and the engine cylinders, the connection 'being made conveniently with the intake manifold, 62, and the suction pipe is provided with a check Valve, 66, opening in a direction toward the manifold. The aperture, 11, of the valve casing is in communication With a source of higher fluid pressure, which in this instance is the atmosphere. ln the released position of the valve mechanism which is illustrated in Fig. 3, the valve, 40, which is the higher pressure valve, is held in open position by the retracting spring, 89, of the foot lever, the collar, 28, being in engagement with the adjusting sleeve, 21, and valve sleeve in engagement with the stop, 91. The valve actuating sleeve, 20, is connected by a pipe, 67, also flexible, with the closed end of the cylinder, and the valve, 40, being in open position,.the cylinder is in communication with the atmosphere. Both faces of the piston and the opposite faces of the closed end of the cylinder are subjected to atmospheric pressure, and the pressures in the 'actuator are equalized. To effect an. application of the brake mechanism by power, the operator will depress the foot lever, thereby moving the valve casing, 10, rearwardly in the direction of the arrow in Fig. 3, with respect to the valve actuating sleeve, closing the air inlet valve, 40, and thereafter opening the suction valve, 41, so as to connect the cylinder with the suction pipe, 65, leading to the intake manifold. Assuming that the engine is running and the throttle valve is closed or partly closed, the air will be eX- hausted `from the cylinder, 1, and the atmospheric pressure on the outer face of the piston and the cylinder, head will effect the movement of the cylinder and piston toward each other, thereby applying the brake mechanisms, B, B1, simultaneously, and equalizing the amount of pressure exerted by said power actuator regardlessof the adjustment of the brake bands or the wear of the braking surfaces. The stroke of the piston in the cylinder is made sufficiently long to insure the application of both brake mechanisms to their maximum extent by power, regardless of the wear of the braking surfaces, without bringing the `piston into contact with the head of the cylinder and therefore it will be unnecessary to adjust the brake mechanisms or to give them any special attention, except to replace the brake linings when suiiciently worn to require replacement. As the brakes are applied by power, the arms, 81, of the three armed levers, L, L, will be moved rearwardly, causing a rearward movement of the link, 84, the link, 76, the valve mechanism and the lower end of the pedal lever, 88, the

` upper end of the lpedal lever moving in a forward direction with thefoot othe operator and following up the application of the brakes by the power actuator without necessarily applying the physical force of the operator to the brake mechanisms. When the brakes have been fully applied by the power actuator, the operator may, however, apply his physical force ,to the vpedal leverand thereby to the equalizin link, 84, which will transmit his physical orce equally to the arms, 81, of the levers, L, L, and through the arms, 80, thereof to the brake mechanisms, thus permitting the operator to apply his physical force in addition to that exerted by 'the actuator, whenever' desired, and to distribute it equally to the brake mechanisms, B, B1, as in making emergency stops and in l applying the brakes when the vehicle is unusually heavily loaded, for example. vIt will alsorbe seen'that should power ail for any reason, the operator can depress the foot pedal, so as to take up the lost motion between the valve casing and the valve actuating sleeve, 20, which will shift the valve l mechanism in position to vent the cylinder and l reventA5 the accumulation `of pressure therein by the relative movements of the piston and cylinder, and can apply his physical force directlyto both brake mechanisms through. thel equalizing link,^84, and the respective three armedlever, L, L. y 4

The only adjustment which need be made at vanytime in brake mechanism embodying our present invention vis that provided by the va stop,

turn buckle, 7 8,oi` its equivalent, by which the e'ective length of 4the link, 76, between the valve mechanism, which is provided with 91which determinesthe ed position of thehrakes, and the equalizing link,`84,

may be varied when necery, to prevent the l.toot lever 'ii-om reaching its limit of movement, which is usually determined hy the pedal coming in contact with the door board, before the brakes are fully applied, to the maximum extent by the physical force oi 'the operator.

pipe, 165, witlrthe According to our invention in which the cylinder and piston are both movable and are each connected with one of theA brakemechanisms to be operated, a smaller, cheaperand lighter power actuator can be employed for a given power, and consequently less air will have to be withdrawn from the actuator and discharged into the intake manifold to effect the operation of the brake mechanisms, thus tending to prevent interference with the operation of the internal combustion engine, or the possibility of stalling it if idling, which would put an end to the suction on which the operation of the brake mechanisms depends. Our invention also provides an equalization of the power applied to both brake mechanisms and through them to the wheels when actuated by power or by the physical force of the operator, or both, thus obviating the necessity for individually adjusting said brake mechanisms to secure an equal application thereof, and by making the cylinder of sullicient length to provide for the maximum application of the brakes, regardless of the wear of the braking surfaces. The adj ustment of the brake mechanisms will ordi-` narily be unnecessary, and only the replacement ofworn brake linings or shoes willvbe required. Only one adjustment is necessary to compensate for the normal wear of the y, brake linings to wit, the wing nut, 78, o the turn buckle, Z7

In Figs, 4, 5 and 6we have shown-a slightly I modified construction in which the connection between the brake mechanism andthe foot lever is made above the point of pivotin of the latter, instead of below the point -o pivoting, as in Figs. 1, 2 and 3. In these figures' the partscorresponding with those shown in 1, 2 and 3 and previously described have been given the same reference numeralswith the addition of 100 to avoid. unnecessa re etition. In this construction thelink, 1 5, rom the valve casing, 110, to the pedal lever, 188, is connected to the lever above its point of pivoting, so that the depression of the pedal exerts a" pull on the valve casing in the direction/- of the arrow in Fig. `6, instead of a rearward push as in the construction shown inFigs. 1, 2 and 3. This necessitates ,thev connection of the suction aperture, 111,- of the valve casing, the aperture, 112, being open to the atmosphere, and arrangement of the adjustable stop, 191, supported'by'the bracket, 192, secured to the chassis in such position that it will engage the rear face oi the collar, 193, on the valve actuating sleeve, 120, so as to limit its rearward movement as shown in Fig. 5. In' the ncriinal or released position of the valve mechanism which is indicated in Fig. 6, vthe valve, 140, which becomes the suction valve will be maintained in closed position, while the valve, 141, which becomes the higher pressure inlet valve will be maintained in open position and connect the cylinder, 101, of the actuator with the atmosphere (or other source of higher pressure) through the hollow valve actuating sleeve,

120, and the flexible pipe, 167. rll`he valve' being connected by a link, 195, with the center of the equalizing link, 184, as shown in Figs. 4 and 5, so that a forward movement of the link, 176, will produce a rearward movement of the equalizing link, 184. The other parts of the apparatus illustrated in Figs. 4, 5 and 6 are constructed as hereinbefore described, and the operation of the mechanism is exactly the same with the exception that the draft on the link, 175, connected with the valve casing and on the link, 176, (when the operator applies his physical force through it to the brake mechanism byA taking up the lost motion between the valve actuating sleeve, 120, and the valve casing) will be in a. forward direction, and the lost motion referred to will be limited in this instance-by the arrangement of the collar, 128, on the valve actuating sleeve with the adjustable collar, 121,' in the rear end of the valve casing.

Our invention is also applicable to a brake system for automotive vehicles in which the operator operated part is connected, by means providing lost motion, with brake mechanism other than the brake mechanisms with which the power actuator is connected. For example, we have illustrated in Fig. 7 diagrammatically such a construction, the parts corresponding withv those previously described l and illustrated in Figs. 1, 2 and 3 being given the same reference characters with the addition of 200. ln this construction the rear or` `of usual or well known'rconstruction, the

brake mechanism for the propeller shaft may, however, be of any desired type. @bviously this propellershaft brake mechanism will apply braking force to both of the rear wheels'through the differential gearing in a well vknown manner, and the differential aeoaaee gearing also acts as an equalizing device to distribute the braking force of the propeller shaft brake mechanism between the rear wheels.

ln this instance the rear wheels are also provided with the independent brake mecha,- nisms, B, B1, as previously described, which are connected by the links, 274, to the outwardly ext-ending arms, 280, of the levers, L, L, which in this instance have only two arms, the forwardly extending arms, 282, being operatively connected with the cylinder and piston respectively of the power actuator in the manner previously described. In this instance the link rod, 276, from the valve actuating part of the controlling valve mechanism for the actuator, instead of being connected with the br-ake mechanisms, B, B1, Y

operated by the actuator, is connected, as shown, to the lever, 272, of the propeller shaft brake mechanism. rlhe operation of the brake system shown in Fig. 7 will be exactly the same as thatpreviously described except that when the lost motion provided in the connections between the operator operated part and the propeller shaft brake mechanism, B2, is t-aken up, the physical force of the operator may be used to supply y braking forces for the rear wheels, W, W1, through the propeller shaft brake mechanism, in addition to the power exerted by the power actuator on the independently operable brake mechanisms, B, B1, for said wheelsgl/V, VW, and in case of failure of power the physical force of the operator may be used to supply braking forces for` the rear wheels, W, lVl, by operating the propeller shaft brake mechanism, B2, without operating the brake mechanisms connected with the power actuator.

lt will be understood that our invention is also applicable to installations in which the power actuator piston is exposed on both faces to the lower pressure fluid, such -as is illustrated for example in Figs. 1 and 2 of our former Letters Patent of the United States, No. 1,731,041, hereinbefore referred to. and it will be also understood that the cylinder may be movably supportedy from and with respect to the chassis, and the cylinder and piston connected by cables passing arornd sheaves of pulleys mounted on the chassis instead of operating through levers as previously described. iin Fig. 8 we have shown a diagrammatic view similar to Fig. 7 in which' the parts corresponding to those shown in Figs. 1, 2 and 3 are given the same numerals with the' addition of 300, and which illustrate the foregoing modifications. ln this instance the actuator cylinder, indicated at 301, is closed at both ends, the outer i tion passage. The valve mechanism will occupy the position shown in Fig. 6, 'when in' released position, the aperture forward of the valve chamber being connected with the atmosphere., the aperture in rear'of the valve chamber being connected by a pipe, 365% with the cylinder forward of the piston, while the hollow valve actuating sleeve is connected by the pipe, 367, with the cylinder in rear of the piston, thereby connecting the ends of the cylinder' on opposite sides of the piston with each other-'and with thesuction passage of the enginel when the valve is 1n the released position shownin Fig. 6.V

rl'he cylinder, 301, and the viston therein are' supported in this instance rom the chassisofthe vehicle by means permitting the cylinder and piston to move with respect to the chassis and with -respect to eachV other.

ln this instance we have` shownthe chassis provided with a grooved guide, indlcated at 306,-to receive a slide bracket, 307, secured to the cylinder, 301, of the actuator. The rear or non-steering wheels, W, W1, are shown as provided with the brake mechanisms, B, B1, constructed as hereinbefore described, the operating levers, 372, of Said brake mechanisms sheaves, 382, mounted on the chassis with the cylinder, 301,and with/the piston rod, 395, of thepiston, 303, respectively. In th1s 1nstance for convenience of illustration, the

link, 37 6,. from the valve acuatin sleeve is connected to the operating arm, 3 2, of propeller shaft brake mechanism, B2, as in Fig.

7. The operation of the construction illustrated in Fig. 8 will be the same as that pre.- viously described with reference to Fig.. 7, so far as the application of the brakes is concerned, but it will be understood that as the..

portion of the cylinder forward of the piston is at all times connected with the suction passage of the engine, the piston will be exposed on both faces to suction, or in other words the lower fluid pressure, whenin. released or ed position. In order to accomplish this result the suction pipe, 365m, is conf nected to the valve casing adjacent tothe open valve, 141 (Figt) so as to connect the pipo, 367, leading vto the cylinder on the opposite side vot the piston, with suction in the released osition. Theforward movement of `the peda to apply thepbrake mechanisms, B, B1, by power, will disconnectY the two ends being connected in thisv instance by cables, 374, 374,.passing around andwith the suction passage of the engine,

to eEect an equalization of pressures within the'cylinde'r and to withdraw the air previously admitted, and permit the brakes to relieve themselves and be returned to their released position with the piston and cylinder under the action of the retracting means for the brake mechanisms, B, B1. The physical force ot' the operator may also be applied to the wheels, W,^W1, as before described, in this instance through the propeller brake Fechgnism as described with reference to The construction illustrated in Figs.- 7 and 8 is not specifically claimed herein as it forms the subject matter of a divisional application liled by us .April 16th, 1929, Serial No. 355,618.

What we claim and ters Patent is f 1. In a brake system for automotive vehicles provided with an internal combustion engine having a throttle controlled suction passage from the carburetor to the engine cylinders, vthe combination with separate brake mechanisms for a pair of wheels mounted on one of the axles of the vehicle, of a power lactuator comprising a cylinder and piston `both movable'with respect'to each other, connections from the cylinder to 'one of said brakemechanisms, connections from the piston to the other of said brake mechanisms,

controlling valve mechanism for said actu,

by meansproviding sucient lost motion to insure the operation of said valve mechanism, said actuator piston having a power stroke of sucient length to compensate tor the wear .oi the braking surfaces, and an adjusting desire to secure by Let-v device in the connections between the oper ator operated part and said power equalizing and'distributing device, whereby the power of the actuator or-of the operator, or botl.

may be simultaneously and equally ap lie to theV brake mechanisms regardless o the wear ot the braking surfaces, and the adjustment ot said adjusting device will compensate tor all wear of braking surfaces of the brake mechanisms, to maintain the parts in operative ositions.

2. du a brake system tor automative vehicles provided with an internal combustion engine havin a throttle controlled suction passage from t e carburetor to the enginecylinders, the combination with separate brake mechanisms for apair of wheels mounted on one of the axles of the vehicle, a pair of pivoted levers each provided with three arms and a piston operatively connected with the corresponding arm of the other of said levers, controlling valve mechanism for the actuator, means for connecting a closed vend of the cylinder on one sideof the piston with the suction passage of the engine between the throttle valve'and the engine cylinder and with the source of higher fluid pressure under the control of .said valve mechanism, an operator operated part connected with said valve mechanism, said levers being each provided with an equalizing arm, -an equalizing link pivotally connected at its opposite ends with said equalizing arms/ and having its central portion connected with the operator operated part by means providing suiiicient lost motion to insure the operation of the valve mechanism, and an adjusting device in the connections between the operatorpoperl ated part and said equalizing link.

3. lin a brake system for automotive vehicles, the combination with brake mechanisms for a pair of wheels disposed oppositely to cach other transversely of the vehicle, of a power actuator comprising a cylinder and piston, both movable with respect to each other and with respect to the vehicle, connections from the cylinder tobrake mechanism for one of said wheels, connections from the piston to brake mechanism for the other of said wheels, controlling valve mechanism for the actuator, provided with relatively movl able parts having a limited movement with respect to each other, means for establishing differential fluid pressures on opposite faces of said `piston and said cylinder under the `Control of said valve mechanism, an operator operated part, connected with one of said relatively movable valve parts, and connections from the other of'said relatively movable valve parts to both of said brake mechamsms. v

4glln a brake system lfor automotive vehicles, the combination with brake mechanisms 4for a pair of' wheels disposed oppositely to each other transverselyl of the vehicle, of a power actuator comprising a cylinder and piston, both movable with respect to each other and with respect to the vehicle, connections from the cylinder to brake mechanism for one of said wheels', lconnections from the piston to brake mechanism for the other of said wheels, controlling valve mechanism for theactuator, provided with relatively movable parts having a limited movement with respect to each other, means for establishing 'diierential luidpressures on opposite faces of said pis-ton and said cylinder under the control of said valve mecha nism, an operator operated part, connected with one of said relatively movable valve parts, and connections from the other of said relatively movable valve parts to both of saidV brake mechanisms, anda single adjusting device in the connections between the operator operated part and said brake mechanisms.

5. In a brake system for automotive vehicles, the combination with brake mechanisms for a pair of wheels disposedC oppositely to cach other transversely of the vehicle, of a power actuator comprising a cylinder and piston, both movable with respect to each o th-l er andwith respect to the vehicle, connections from the' cylinder 'to brake mechanism for o ne ofl said wheels, connections from the'piston to brake. mechanism for the -other of said Wheels", controlling valve mechanismfgforthe actuator, provided with relatively movable. parts having a limited movement respect i, to each other, means for establishingI dierential fluid pressures on opposite faces of said piston and said cylinder under the control of said valve mechanism, an operator operated part, connected with one of saidrelatively movable valve parts, connections from the y other of said relatively movable valve part to sa-id brake mechanisms, including equalizing means, and asingle adjusting device in said last mentioned connections interposed between said equalizing means and the valve part-connected therewith. i

6. In a brake system for automotive vehicles, the combination with separate brake mechanisms for a pair of wheels mounted on one of the axles of the vehicle, offl a power actuator comprising a cylinder and iston both movable with respect to the vehicle, a pair of pivoted multiple arm levers, each having one arm operatively connected with que brakel mechanism, said cylinders being pivot` ally connected and supported by another arm of one of said levers, and the piston being operatively connected with a corresponding arm of the other of said levers, an equalizing link operatively connected with the third arm of eac-h of said levers, a valve mechanism for the actuator, means fior connecting a. closed end of said cylinder-on one side of the piston icc its

with sources of higher and lower fluid pressures under the control of said valve mechanism, and an' operator operated part connected with vsaid valve mechanism, and connected with the said equalizing link by means providing initial lost motion'suiicient to inl f sure the operation of the valve mechanism.

f 7. ln a brake system for automotive vehicles, the combination with separate brake mechanisms for a pair of wheels mounted onv one of the axles of. the vehicles, of a. power actuator comprising a cylinder and piston both movable with respect to the vehicle, a pair of pivoted multiple arm levers, each having one arm operatively connected with one brake mechanism, said cyllnder being y. pivotally' connected and supported by another arm of one ofsaid' levers and-the piston heinigl operatively connected with a corresponding arm on the other of said levers, an equalizing link operatively connected with the third arm of each of said levers, a valve mechanism for the actuator, means for connectinga closed end of said cylinder on one side of the piston with sources of higher and lower fluid pressures under the control of said valve mechanism, and an` operator operated part connected with said valve mechanism having limited movement, and connected with the said equalizing device by means providing initial lost motion sucient to insure the operation of Ithe valve mechanism, the piston having a s'ucient stroke in said actuator cylinder to compensate for Wear of the braking surfaces,

and an adjusting device in the connections loetvveen the operator operatedpart'and said equalizing link to compensate' for the vvear of the braking surfaces Withrespect to said limited movement of said operator operated part.,

ln testimony whereof we amr `our signaturesB CAL'EB S. BRAGG., VICTR/W. KLlllESRA'lFH. 

